Producing luminescent images by electroluminescence



April 7, 1959 H. A. MlCHLlN 81,353

PRODUCING LUMINESCENT IMAGES BY ELECTROLUMINESCENCE Fil'ed Jan. 9, 1952 INVEN'ITOR United States Patent PRonUcrNG LUMINESCENT IMAGES Y ELECTROLUMINESCENCE This invention relates to the art of electron beam scanning of luminescentphosphor screens to produce luminescent images thereon; and in particular to producing such luminescent images byblectroluminescenc'e on alayer of electroluminescent phosphors having stored therein luminescent excitation energy. i As far as is known in the present state of the art; high voltages are used to impart high electron velocity to a video modulated electron beam scanning a raster on a phosphorescent screen. This produces an emission of radiant energy in the form of visible light rays to form a luminescent image; and, in addition, an emission of other forms of radiant energy harmful to the physical visual process by causing eyestrain andphysical hurt to the optic nerves and other parts of the physical visual process. This invention seeks to remedythis by storing luminescent energy in phosphors and using the principle of electroluminescence with old elements in a new and useful combination to produce luminescent images without such harmful radiations; and also to reduce the cost of manufacture by using comparatively much lower electron velocity and therefore much lower voltages.

Briefly, the primary object of this invention is the producing of electric potential diiference between scanned elemental areas on ,an anisotropic conductive layer and corresponding elemental areas on a conductance layer; with electroluminescent phosphors, irradiated by. luminescent excitation energy so as to store the luminescent excitation energy therein, interposed-in the path of said electric potential differences between theanisotropic conductive and conductance layers; and said phophors luminescing in proportion to the electric energy impressed on and transmitted through said electroluminescent phosphors. Phosphors that can be caused to luminesce by electroluminescence can also be caused to luminesce by cathodoluminescence with the former producing luminescence by a difierence in electric potential levels and the transmission of electric energy therethrough, and the latter by bombarding electrons of difierent velocities to impart electric energy effects thereon. It is evident that both methods impart electric energy to phosphors to produce luminescence therein. Phosphors irradiated with luminescent excitation energy, so as to have such energy stored therein, produce, when subjected to electroluminescence or cathodoluminescence, a brighter luminescence than when said phosphors have not any luminescent excitation energy stored therein.

transmission of electrons through it and resists the flow of electrons laterally. The said lateral resistance being sufiicient to preserve the charge configuration impressed thereon by and in image of a scanning modulated electron beam, and suflicient to induce a flow of electric energy to each scanned elemental area of the anisotropic conductive layer 6 from a higher level of electric potential on conductance layer 4 and vice versa through CICCiIO? luminescent matter 5 interposed between the anisotropic conductive layer 6 and the conductance layer 4 between elemental areas of which there is produced difierent levels of electric potential representative of a video signal energy to produce luminescence in image of the video signal energy until the charge on each scanned elemental area on the anisotropic conductive layer 6 is brought to a level of electric potential in relation to the level of the electric potential on the layer of conductance on 'the op: posite side of the electroluminescent matter so that elec troluminescence is not produced. The Image Orthicon tube uses a target of very thin glass to preserve the charge configuration on said target for the duration of the frame interval;'and this target can also be used as an anisotropic conductive layer as the electric energy is transmitted through the image orthicon tube target while maintaining its charge configuration.

-In brief the novel combination lies in the layers of the anisotropic conductive layer 6, electroluminescent matter 5, conductance 4, and, a source of luminescent excitation energy 7; and any combination of said elements of the novel combination.

In Figure 1 the envelope 1 of the picture tube hold therein electron beam scanning and projection means, and, electron collecting means 2. The scanning electron beam 3 modulated by a video signal energy from 9, bombards a layer of the anisotropic conductive layer 6 to vary the charge thereon by imparting electrons thereto. A layer of electroluminescent phosphors 5, for ex ample ZnSCu and ZnMnS, storing luminescent excitation energy, for example short wavelength rays, continuously irradiated on it by luminescent excitation energy source 7, is interposed between the layers of the anisotropic This is a continuation-in-part of application Serial No.

conductive layer 6 and the conductance layer 4, said conductance layer 4 being transparent to light rays. The said layer of conductance 4 is impressed by electric energy of such electric potential level from electric energy source 8 that there will be a fiow of electricity through the layer of electroluminescent phosphors 5 'to or from the scanned elemental areas on the anisotropic conductive layer 6 in a direction from the higher electric potential level to the lower electric potential level so as to produce electroluminescence in image of the electric potential difference between each scanned corresponding elemental area of the anisotropic conductive layer and the conductance layer 4.

To illustrate, by way of example, a method of operation. The electron beam 3, modulated by a video signal energy from signal energy source 9 and of low velocity to cause imparting of primary electrons on to each elemental area of the anisotropic conductive layer scanned, scans the anisotropic conductive layer 6 to produce an electric potential charge in image of the signal modulating the electron beam. The conductance layer 4 has impressed thereon electric energy of sufiicient high potential level so as to cause a flow of electric energy from the anisotropic conductive layer 6 through the interposed layer of electroluminescent phosphors 5 to the layer of conductance 4; as to cause electroluminescence the intensity of which varies with the intensity of the difference in electric potential and the intensity of electric energy transmitted therethrough. This flow of electric energy is continued until the primary electrons imparted by elec-.-

tron beam 3 is transmitted through the electroluminescent phosphor layer 5 to the conductance layer 4 to electric potential source 8. As the scanning of the electron beam ,,prog resses a luminescent image representative of the video signal energy is formed, Although the drawing shows a luminescent excitation energy source 7 outside, the tubev envelope; it can also be placed inside the, tube enve p A modification of the above can be had by modulating the, electric energy impressed on the conductance layer 4 by the video signal energy and by giving the electrons in the electron beam 3 a constant high or low velocity to cause secondary emission of electrons or imparting primary electrons respectively. Another modification is the interposing between the layers of the anisotropic conductive layer 6 and the conductance 4 electroluminescent gases or liquids, to. pro-. dnce a luminescent image. Substances sensitive to elec-v tric force or energy so as to alter its physical or chemical properties so as to produce an image, thereon when sub: jected to electric energy or force and supported on a film otinsulation material, as in photography where sensitiveness is to. the light rays, and interposing said. electric sensitive substances supported on film or insulation ma-. terial between said layers of anisotropic conductive layer 6 and. conductance layer 4 during the interval of time that a video signal energy is impressed thereon will pro duce an image thereon.

The drawing and specification are for illustration purposes and is not to be construed as restrictive; and there fore while I have disclosed several. particular means to practice my invention, it will be obvious that other structures may be of equal advantage, and, I therefore donot wish, to be limited to the particular modifications, set forth above except as my invention is so limited by the appended claims.

I claim:

1. The method for producing a luminescent image on a luminescent layer by a configuration of electric energies comprising the steps of irradiating the luminescent layer with luminescent excitation energy in radiant energy. to store luminescent excitation energy therein; impacting electron energies on one side of the luminescent layer to impress the configuration of electric energies in potentials thereon, and applying an electric energy in a dilfen entpotential to the opposite side of said one side of the luminescent layer to effect suflicient potential dilferences; therebetween so as to eifect a configuration of lines of electric forces through the luminescent layer, in accord-. aneewith the potentials of the impressed configuration of electric energies on one side and the potential of electric energy on the other side of the luminescent layer, to substantially effect a transmission of the configuration of electric energies through the luminescent layer to effect a luminescent image the light values of which are in image of said substantially transmitted configuration of electric energies.

2. The method for producing a luminescent image on a luminescentlaycr, by aconfigurationof electric energies converted from and in image of impacting electron energies comprising the steps of irradiating the luminescent layer with luminescent excitation energy in radiant energy to store luminescent excitation energy therein; impacting a configuration of electron energies on a layer, capable of transmitting a configuration of electric energies in potentials therethrough, on one side of said luminescent layer to impress a configuration of electric energies in potentials on saidlayer in image of the impacting; electron. energies. and to transmit the configuration of electric energies therethrough; and applying an electric energy in a difierent potential to the opposite side oi said one side of said luminescent layer to effect sufficient potential differences between, both sides of said luminescent layer so asv to effect a configuration of differences in electric energy potentials, in accordance with the poten tials of the impressed configuration of electric energies on one side and the potential of electric energy on the other side of the luminescent layer, to substantially effect a transmission of the configuration of electric energies through. said luminescentlayer to effect a luminescent image the light values of which are in image of said substantially transmitted configuration of electric energies.

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